Embodiments of the present invention relate to setting the value of an operational parameter of a well, such as a hydrocarbon production or injection well.
The safe and efficient operation of an offshore oil or gas well relies on a knowledge of the reservoir characteristics and the ability to control the flow of fluid from the well. The flow of fluid from a reservoir is controlled by means of hydraulically operated valves (or chokes) positioned within the well, usually at the depths of the various reservoir zones, so that fluid can be drawn from each zone as required into the main well borehole. A choke at the wellhead controls the flow of fluid from the well itself. The rate of flow of fluid from a well depends on various parameters, such as the well fluid pressure and the operating conditions, both upstream and downstream. These must be taken into account when determining the optimum flow requirements at any one time and it must also be ensured that the design parameters of the subsea control system and the overall system are not exceeded. For these reasons, a significant amount of operator time is spent manually positioning chokes to optimize production, whilst not exceeding the design and operational limits of the system through which the fluid flows.
Present methods of controlling and determining the choke positions use complex optimization algorithms to set a choke or recommend choke positions to an operator. Maximum and minimum limits are added as constraints to the optimization solution. These algorithms are numerically complex, difficult to tune, and are often not robust to changes in system operation.